()

Description

 

Resources

158 resources available. Click on the image to preview, click on the publisher link to download.

Seed treatment of damping off of tomato

20197800162.jpg

FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Afghanistan, March 2017 Seed Treatment of Damping off of Tomato Recognize the problem Damping-off is generally limited to areas where drainage is poor or where soil is compacted, but whole fields can be affected, especially in early plantings when exposed to rain. Seedlings affected by damping-off fail to emerge or fall over and die soon after emergence. Stems usually have a dark, shrivelled portion at the soil line. Background "Damping-off" is a general term for the death of seedlings, either before or after emergence, under damp...

Published at: plantwise.org

Botanical control of tomato leaf miner

20197800163.jpg

FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Afghanistan, March 2017 Botanical Control of Tomato Leaf Miner Recognize the problem Originating from South America, Tuta absoluta is a devastating pest on tomato crops. Recently, Tuta absoluta was considered to be a serious threat to tomato production in the southern region of the country as it can largely damage the crop and reduce the yield. Background Tuta absoluta is a micro lepidopteron moth with a high reproductive potential. There are between 10–12 generations per year, with the total life cycle completed within 30-35 days....

Published at: plantwise.org

Protective sprays for bacterial spot on tomato

20177801113.jpg

FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Zambia, July 2017 Protective sprays for bacterial spot on tomato Recognize the problem Bacterial spot disease may appear wherever tomato and peppers are grown. It affects leaves, stems, fruits, seeds and flowers. Symptoms are small, dark- grey, greasy-looking spots. When severe, leaves shrivel and die. Bacterial spot is similar to another disease of tomato, bacterial speck. Symptoms of bacteria speck are small dark spots, initially surrounded by a yellow halo, whereas bacterial spot disease does not have this halo. In contrast, fungal...

Published at: plantwise.org

How to develop a pest scouting calendar

20177800667.jpg

FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Zambia, September 2016 How to develop a pest scouting calendar Recognize the problem Many different pests and diseases affect crop growth, leading to poor yields. Some farmers notice their presence a bit late. This makes the pest control more costly or sometimes impossible. This is due to the farmer’s failure to scout and monitor their fields at specified regular intervals such as once in a week. Background Scouting involves regular visits to a field from planting onwards to monitor the health of the crop. It identifies the presence...

Published at: plantwise.org

Potato bacterial wilt control

20177800510.jpg

FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Afghanistan, February 2016 Potato Bacterial Wilt Control Recognize the problem Bacterial wilt is economically a very important disease of potato throughout the world and was first reported in 1896 in the United States of America. Potato growers face losses from their potato production as a result of this disease. In some countries in Africa, Asia and Latin America, bacterial wilt is endemic, and this disease can be caused by different species of bacteria. Background Bacterial wilt is caused by bacteria that attack brinjal, tobacco,...

Published at: plantwise.org

How to take a soil sample for analysis

20177800427.jpg

FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Zambia, September 2016 How to take a soil sample for analysis Recognize the problem Farmers experience deficiencies of nutrients such as phosphorous, calcium, magnesium and other deficiencies in their fields which reduce plant growth and yield. To address these deficiencies, professional soil testing is required to understand which soil nutrients are present at what quantities in the soils and which ones are not enough for plant growth. However, many farmers do not know how to collect and send the soil samples required for soil...

Published at: plantwise.org

Using Tithonia as a green manure in tomato

20167800165.jpg

FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Zambia, July 2015 Using Tithonia as a green manure in tomato Recognize the problem Tomato requires a lot of fertilisation to yield well. The major nutrients are potassium, phosphorous, nitrogen and calcium. Background Fertilisation of tomatoes is needed, but synthetic fertilizers increase the cost of producing the crop. Other means of fertilization can help to reduce the costs. For example, planting green manure plants can help to improve the soil. Tithonia plants are one such option. Tithonia, also known as Mexican sunflower, is a...

Published at: plantwise.org

Management of potato late blight

20157801442.jpg

FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Myanmar [Burma], June 2014 Management of Potato late blight Recognize the problem Late blight disease affects all of the aerial parts of potato plants and starts at the tip or the margin of leaves and then develops into water-soaked lesions. Within a few days, the lesions become necrotic, turning brown when dry and purplish-brown when wet. White mildew-like sporulation is visible around the lesions, especially on the lower surface of the leaves. Lesions on stems and petioles are black or brown. Tubers show brown to purplish skin and...

Published at: plantwise.org

Calcium against blossom end rot of chillies & tomatoes

20157800257.jpg

FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Pakistan, June 2014 Calcium against Blossom end rot of Chillies and TomatoesRecognize the problem Blossom end rot of chillies and tomatoes is a problem that is caused by calcium deficiency. During blossom end rot, the skin of the fruit becomes fragile. The skin at the end of the fruit where the flower grew splits, rots and develops a circular spot. The rot causes the skin of the fruit to turn greenish brown to black. As the rot expands, it allows other diseases to enter the fruit which affects the production of the crop. Background...

Published at: plantwise.org

Reducing tomato bacterial wilt in your field

20157800103.jpg

FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Democratic Republic of the Congo, May 2014 Reducing tomato bacterial wilt in your field Recognize the problem Tomato is one of the most imprtant fruits in the world. Unfortunately, it is affected by a virulent disease: bacterial wilt. This bacteria reduces plant yields and eventually kills the plant. It causes the stem to soften and leaves to wilt and fall. We also see black or brown spots on and inside the stem. The plant dies when the disease is at an advanced stage. Background This disease is caused by a bacteria that lives near...

Published at: plantwise.org

Management of damping off disease in tomato

20157800327.jpg

FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Ethiopia, August 2014 Management of Damping off Disease in Tomato Recognize the problem Damping off is a major disease of young tomato seedlings and losses can reach 80 - 100%. The disease can be caused by several different pathogens (Pythium, Phytophthora and Rhizoctonia species) but the same symptoms occur. The seedlings either fail to emerge from the soil or fall over and die immediately after emergence. Background These fungal pathogens can survive for several seasons in wet soil. Poor drainage, compacted soil and inadequate air...

Published at: plantwise.org

Sprays against Tuta tomato leaf miner

20157800364.jpg

FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Tanzania, October 2014 Sprays against Tuta tomato leaf miner Recognize the problem Tomato leaf miner is a devastating pest of tomatoes. It is also known as Tuta absoluta, Tomato moth, or kidomozi wa nyanya in Kiswahili. Tomato leaf miner adults are small silver-grey moths with black spots on their inner wings. They are about ½ cm long and have wings of about 1 cm if spread. They hide under leaves in the daytime. Young larvae in the tunnels are creamy-greenish with a dark head but later turn pinkish-green. They are tiny and feed in...

Published at: plantwise.org

Disposing of fruit to manage Tuta absoluta on tomato

20157800394.jpg

Published at: plantwise.org

Minerals against blossom end rot in tomato

20167800162.jpg

Published at: plantwise.org

Prevention of sunscald in pepper

20167800164.jpg

Published at: plantwise.org

Management of leaf miner fly

20157800048.jpg

Published at: plantwise.org

Management of whitefly

20157800054.jpg

FACTSHEETS FOR FARMERS www.plantwise.org Created in Nepal , May 2014 Management of Whitefly Recognize the problem Whitefly adults are tiny (about 1 mm long) moth-like insects. They are white to slightly yellowish in colour and their bodies and both pairs of wings are covered with a powdery and waxy secretion. They suck cell sap from the lower surface of the leaves. The symptoms of whitefly infestation are yellowing of leaves, withered plant parts and reduced flowering and fruiting. Sticky substances appear on the leaf surface and sooty mold...

Published at: plantwise.org

Whitefly

20157800238.jpg

FACTSHEETS FOR FARMERS www.plantwise.org Created in Bangladesh , September 2013 Whitefly Recognize the problem Whitefly is the most damaging pest of many vegetable and horticultural crops, including chilli, tomato, papaya and guava. The whitefly is a small white insect, which lives underneath the leaves. If the plant is gently shaken, the whiteflies will fly away and so are easy to see. Too many whiteflies can destroy the total crop. When the whitefly sucks on the plant, it can inject viruses into the plant. Viruses make the plant curl at the...

Published at: plantwise.org

Early blight of tomatoes

20157800164.jpg

Tomato fruit borer

20157800176.jpg

Pages

Filter by related pathogen:

Names

Solanum lycopersicum in differrent languages.

Golbheda
Mtunguja
Mtungule
Nyanya
Tamatar
Lycopersicon esculentum
Lycopersicon lycopersicum
Lycopersicum esculentum
Lycopersicum lycopersicon
Lycopersicum lycopersicum
Solanum lycopersicon
Jitomate

Q&A

Description

Eggs;Eggs are pear shaped with a pedicel spike at the base, approximately 0.2 mm long.;Puparium;A flat, irregular oval shape, about 0.7 mm long, with an elongate, triangular vasiform orifice. On a smooth leaf the puparium lacks enlarged dorsal setae, but if the leaf is hairy, 2-8 long, dorsal setae are present.;Adult;Adults are approximately 1 mm long, the male slightly smaller than the female. The body and both pairs of wings are covered with a powdery, waxy secretion, white to slightly yellowish in colour.

Symptons

Early indication of infestation may consist of chlorotic spots caused by larval feeding, which may also be disfigured by honeydew and associated sooty moulds. Leaf curling, yellowing, mosaics or yellow-veining may also indicate the presence of whitefly-transmitted viruses. These symptoms are also observed in B. tabaci infestations, however phytotoxic responses such as a severe silvering of courgette and melon leaves, mis-ripening of tomato fruits, stem whitening of brassicas and yellow veining of some solanaceous plants may also be seen (Costa et al., 1993, Secker et al., 1998).;The feeding of adults and nymphs causes chlorotic spots to appear on the surface of the leaves. Depending on the level of infestation, these spots may coalesce until the whole of the leaf is yellow, apart from the area immediately around the veins. Such leaves are later shed. The honeydew produced by the feeding of the nymphs covers the underside of leaves and can cause a reduction in photosynthetic potential when colonized by moulds. Honeydew can also disfigure flowers and, in cotton, can cause problems in lint processing. Following heavy infestations, plant height, the number of internodes, and yield quality and quantity can be affected, for example, in cotton.;Phytotoxic responses in many plant and crop species caused by larval feeding include severe silvering of courgette leaves, white stems in pumpkin, white streaking in leafy Brassica crops, uneven ripening of tomato fruits, reduced growth, yellowing and stem blanching in lettuce and kai choy (Brassica campestris) and yellow veining in carrots and honeysuckle (Lonicera) (Bedford et al., 1994a,b).;A close observation of leaf undersides will show tiny, yellow to white larval scales. In severe infestations, when the plant is shaken, numerous small and white adult whiteflies will emerge in a cloud and quickly resettle. These symptoms do not appreciably differ from those of Trialeurodes vaporariorum, the glasshouse whitefly, which is common throughout Europe.

Host plant resistance

The development of transgenic resistant plant and crop species through genetic engineering must be considered and accepted as a future method of control where whitefly-transmitted viruses are already endemic and causing severe crop losses (Wilson, 1993, Raman and Altman, 1994). Traditional sources of resistance have been used successfully for the control of other whitefly species.


Source: cabi.org
Description

P. hysterophorus is an erect, much-branched with vigorous growth habit, aromatic, annual (or a short-lived perennial), herbaceous plant with a deep taproot. The species reproduces by seed. In its neotropical range it grows to 30-90 cm in height (Lorenzi, 1982, Kissmann and Groth, 1992), but up to 1.5 m, or even 2.5 m, in exotic situations (Haseler, 1976, Navie et al., 1996). Shortly after germination the young plant forms a basal rosette of pale green, pubescent, strongly dissected, deeply lobed leaves, 8-20 cm in length and 4-8 cm in width. The rosette stage may persist for considerable periods during unfavourable conditions (such as water or cold stress). As the stem elongates, smaller, narrower and less dissected leaves are produced alternately on the pubescent, rigid, angular, longitudinally-grooved stem, which becomes woody with age. Both leaves and stems are covered with short, soft trichomes, of which four types have been recognized and are considered to be of taxonomic importance within the genus (Kohli and Rani, 1994).;Flower heads are both terminal and axillary, pedunculate and slightly hairy, being composed of many florets formed into small white capitula, 3-5 mm in diameter. Each head consists of five fertile ray florets (sometimes six, seven or eight) and about 40 male disc florets. The first capitulum forms in the terminal leaf axil, with subsequent capitula occurring progressively down the stem on lateral branches arising from the axils of the lower leaves. Thousands of inflorescences, forming in branched clusters, may be produced at the apex of the plant during the season. Seeds (achenes) are black, flattened, about 2 mm long, each with two thin, straw-coloured, spathulate appendages (sterile florets) at the apex which act as air sacs and aid dispersal.

Hosts

P. hysterophorus is known to reduce the yield of various crops and to compete with pasture species in various countries. However, the yield loss and specific effects on the crops have not been quantified in all countries (Rubaba et al., 2017).;In Australia, the main impact of P. hysterophorus has been in the pastoral region of Queensland, where it replaces forage plants, thereby reducing the carrying capacity for grazing animals (Haseler, 1976, Chippendale and Panetta, 1994). Serious encroachment and replacement of pasture grasses has also been reported in India (Jayachandra, 1971) and in Ethiopia (Tamado, 2001, Taye, 2002). The weed is also able to invade natural ecosystems, and has caused total habitat changes in native Australian grasslands and open woodlands (McFadyen, 1992).;In India, the yield losses are reported as up to 40% in several crops and a 90% reduction of forage production (Gnanavel, 2013). P. hysterophorus is now being reported from India as a serious problem in cotton, groundnuts, potatoes and sorghum, as well as in more traditional crops such as okra (Abelmoschus esculentus), brinjal (Solanum melongena), chickpea and sesame (Kohli and Rani, 1994), and is also proving to be problematic in a range of orchard crops, including vineyards, olives, cashew, coconut, guava, mango and papaya (Tripathi et al., 1991, Mahadevappa, 1997, Gnanavel, 2013).;Similar infestations of sugarcane and sunflower plantations have recently been noted in Australia (Parsons and Cuthbertson, 1992, Navie et al., 1996), whilst in Brazil and Kenya, the principal crop affected is coffee (Njoroge, 1989, Kissmann and Groth, 1992). In Ethiopia, parthenium weed was observed to grow in maize, sorghum, cotton, finger millet (Eleusine coracana), haricot bean (Phaseolus vulgaris), tef (Eragrostis tef), vegetables (potato, tomato, onion, carrot) and fruit orchards (citrus, mango, papaya and banana) (Taye, 2002). In Pakistan, the weed has been reported from number of crops, including wheat, rice, sugarcane, sorghum, maize, squash, gourd and water melon (Shabbir 2006, Shabbir et al. 2011, Anwar et al. 2012).;In Mexico, the species is reported as a weed in cotton, rice, sugarcane, Citrus spp, beans, safflower, sunflower, lentils, corn, mango, okra, bananas, tomato, grapes, alfalfa, chili peppers, luffa, marigolds and other vegetables and fruit orchards. It is also a weed in nurseries. In Argentina is reported as a weed of tobacco fields (CONABIO, 2018).;Gnanavel (2013) also reports the following detrimental effects of P. hysterophorus on crops: it inhibits nitrogen fixing bacteria in legumes, the vast quantity of pollen it produces (ca. 624 million/plants) inhibits fruit setting, it is an alternative host for viruses that cause diseases in crop plants, and it is an alternative host for mealy bugs.

Biological Control
The use of insect and fungal pathogens and the exploitation of allelopathic plants is considered by Kaur et al. (2014) as the most economical and practical way to manage the infestations of the species. Biological control has been, and continues to be, considered the best long-term or sustainable solution to the parthenium weed problem in Australia (Haseler, 1976, McFadyen, 1992) and because of the vast areas and the socio-economics involved, this approach has also been proposed for India (Singh, 1997). South Africa was the first country in Africa to implement a biological control program against the species in 2003 (Rubaba et al., 2017). Four host-specific biocontrol agents have been released sequentially since 2010 after evaluation of their suitability, with variable establishment and spread (Strathie et al., 2016).;The use of insects as biocontrol agents had been tried in various countries (Kaur et al., 2014). Searches for, and evaluation of, coevolved natural enemies have been conducted in the neotropics since 1977. So far, nine insect species and two fungal pathogens have been introduced into Australia as classical biological control agents (Julien, 1992, McClay et al., 1995, Navie et al., 1996, Dhileepan and McFadyen, 1997, Evans, 1997a). Callander and Dhileepan (2016) report that most of these agents have become established and have proven effective in central Queensland, but that the weed is now spreading further into southern Queensland where the biocontrol agents are not present. Several of the agents are therefore now being redistributed into south and southeast Queensland.;The rust fungus, Puccinia abrupta var. partheniicola, is a prominent natural enemy in the semi-arid uplands of Mexico (Evans, 1987a, b), but since its release in Queensland in 1992, climatic conditions have been largely unfavourable (Evans, 1997a, b). It was accidentally introduced into Kenya (Evans, 1987a) and Ethiopia in mid-altitudes (1400-2500 masl) with disease incidence up to 100% in some locations (Taye et al., 2002a). Screening of another rust species (Puccinia melampodii) from Mexico was carried out (Evans, 1997b, Seier et al., 1997) and released in Australia in the summer of 1999/2000 (PAG, 2000). This fungus was later renamed Puccinia xanthii Schwein. var. parthenii-hysterophorae Seier, H.C.Evans & ç.Romero (Seier et al., 2009). Retief et al. (2013) report on specificity testing carried out in quarantine facilities in South Africa, and conclude that the fungus is suitable for release as a biological control agent of P. hysterophorus in South Africa. The authors suggest that this species has more potential for biocontrol in South Africa than Puccinia abrupta, which may have little impact in the low-altitude, high-temperature areas of the country where the weed is spreading.;In India, the mycoherbicide potential of plurivorous fungal pathogens belonging to the genera Fusarium, Colletotrichum, Curvularia,Myrothecium and Sclerotium, has and is being evaluated (Mishra et al., 1995, Evans, 1997a). Parthenium phyllody disease caused by the phytoplasma of faba bean phyllody group (FBP) was reported to reduce seed production by 85% (Taye et al., 2002b) and is being evaluated for use as a biological control agent in Ethiopia. Kaur and Aggarwal (2017) have tested an Alternaria isolate found on the weed, and report that it is worth investigating as a mycoherbicide for control of parthenium. Metabolites of Alternaria japonica and filtrates of Alternaria macrospora have caused significant damage to Parthenium (Kaur et al., 2015, Javaid et al., 2017).;Among the established insect biocontrol agents, the leaf-feeding beetle, Zygogramma bicolorata, the stem-galling moth, Epiblema strenuana, the stem-boring beetle, Listronotus setosipennis, and the seed-feeding weevil, Smicronyx lutulentus, are proving to be the most successful when climatic factors are favourable (McFadyen, 1992, Dhileepan and McFadyen, 1997, Evans, 1997a). Some control of parthenium weed has also been achieved in India with Z. bicolorata (Jayanth and Visalakshy, 1994, Singh, 1997, Sarkate and Pawar, 2006), although there has been controversy concerning its taxonomy and host specificity (Jayanth et al., 1993, Singh, 1997). Shabbir et al. (2016) reported that Z. bicolorata was most effective when applied in higher densities and at early growth stages of the weed. The distribution of this leaf beetle in South Asia was investigated by Dhileepan and Senaratne (2009), when it was present in many states in India, and in the Punjab region of Pakistan. Shrestha et al. (2011) reported that Z. bicolorata arrived in the Kathmandu Valley of Nepal in August 2010, and that by September it had spread over half of the valley areas where P. hysterophorus was present, although damage to the weed was only appreciable at one site.;Z. bicolorata has been seen attacking sunflowers in India and the use of Epiblema strenuata has not been effective, as it was found affecting Guizotia abyssinica crops (Kaur et al., 2014). More recently, Z. bicolorata and L. setosipennis have been released in South Africa and S. lutulentus is being evaluated under quarantine. Before approval as a biocontrol agent in South Africa in 2013, extensive testing suggested that Z. bicolorata would not become a pest of sunflowers in the country (McConnachie, 2015).;The use of antagonistic, competitor plants, such as Cassia spp. and Tagetes spp., has been recommended to control and replace P. hysterophorus in India (Mahadevappa and Ramaiah, 1988, Evans, 1997a, Mahadevappa, 1997, Singh, 1997). In Australia, Bowen et al. (2007) tested a number of grass and legume species against the growth of parthenium weed plants and identified further species that could suppress weed growth. Recently, Khan et al. (2013) tested a number of native and introduced pasture species and identified several of them to be suppressive against parthenium weed in both glasshouse and field conditions. The sowing of selected pasture plants in infested areas can suppress the growth of parthenium weed by as much as 80% and also provide improved fodder for stock (Adkins et al., 2012). Shabbir et al. (2013) showed that the suppressive plants and biological control agents can act synergistically to significantly reduce both the biomass and seed production of parthenium weed under field conditions. The suppressive plants strategy is easy to apply, sustainable over time, profitable under a wide range of environmental conditions and promotes native plant biodiversity. Species reported as effectively outcompeting P. hysterophorus are Cassia sericea, C. tora, C. auriculata, Croton bonplandianum, Amaranthus spinosus, Tephrosia purpurea, Hyptis suaveolens, Sida spinosa, and Mirabilis jalapa. Extracts of Imperata cylindrica, Desmostachya bipinnata, Otcantium annulatum, Sorghum halepense Dicanthium annulatum, Cenchrus pennisetiformis, Azadirachta indica, Aegle marmelos and Eucalyptus tereticornis are reported as inhibiting the germination and/or growth of P. hysterophorus (Kaur et al., 2014).

Source: cabi.org
Description

Fusarium wilt of bananas is caused by F. oxysporum f.sp. cubense, a common soil inhabitant. Other formae speciales attack a wide variety of other crops, including cotton, flax, tomatoes, cabbages, peas, sweet potatoes, watermelons and oil palms.;The formae speciales of Fusarium oxysporum each produce three types of asexual spores. The macroconidia (22-36 x 4-5 µm, see Wardlaw, 1961 for measurements) are produced most frequently on branched conidiophores in sporodochia on the surface of infected plant parts or in artificial culture. Macroconidia may also be produced singly in the aerial mycelium, especially in culture. The macroconidia are thin-walled with a definite foot cell and a pointed apical cell. Oval or kidney-shaped microconidia (5-7 x 2.5-3 µm) occur on short microconidiophores in the aerial mycelium and are produced in false heads. Both macroconidia and microconidia may also be formed in the xylem vessel elements of infected host plants, but the microconidia are usually more common. The fungus may be spread by macroconidia, microconidia and mycelium within the plant as well as outside the plant. Illustrations of the conidia have been published (Nelson et al., 1983).;Chlamydospores (9 x 7 µm) are thick-walled asexual spores that are usually produced singly in macroconidia or are intercalary or terminal in the hyphae. The contents are highly refractive. Chlamydospores form in dead host-plant tissue in the final stages of wilt development and also in culture. These spores can survive for an extended time in plant debris in soil.;Mutation in culture is a major problem for those working with vascular wilt isolates of F. oxysporum. The sporodochial type often mutates to a 'mycelial' type or to a 'pionnotal' type. The former has abundant aerial mycelium, but few macroconidia, whereas the latter produces little or no aerial mycelium, but abundant macroconidia. These cultures may lose virulence and the ability to produce toxins. Mutants occur more frequently if the fungus is grown on a medium that is rich in carbohydrates.

Symptons

Banana;The various symptoms of Fusarium wilt on banana are described and well illustrated by Ploetz and Pegg (1999).;The first external symptoms of Fusarium wilt on bananas is a faint off-green to pale-yellow streak or patch at the base of the petiole of one of the two oldest leaves. The disease can then progress in different ways. The older leaves can yellow, beginning with patches at the leaf margin. Yellowing progresses from the older to the younger leaves until only the recently unfurled or partially unfurled centre leaf remains erect and green. This process may take from 1 to 3 weeks in cultivar 'Gros Michel'. Often the yellow leaves remain erect for 1-2 weeks or some may collapse at the petiole and hang down the pseudostem. In contrast to this 'yellow syndrome', leaves may remain completely green except for a petiole streak or patch but collapse as a result of buckling of the petiole. The leaves fall, the oldest first, until they hang about the plant like a skirt. Eventually, all leaves on infected plants fall down and dry up. The youngest are the last to fall and often stand unusually erect.;Splitting of the base of the pseudostem is another symptom as is necrosis of the emerging heart leaf. Other symptoms include irregular, pale margins on new leaves and the wrinkling and distortion of the lamina. Internodes may also shorten (Stover, 1962, 1972, Jones, 1994, Moore et al., 1995).;The characteristic internal symptom of Fusarium wilt is vascular discoloration. This varies from one or two strands in the oldest and outermost pseudostem leaf sheaths in the early stages of disease to heavy discoloration throughout the pseudostem and fruit stalk in the later disease stages. Discoloration varies from pale yellow in the early stages to dark red or almost black in later stages. The discoloration is most pronounced in the rhizome in the area of dense vascularization where the stele joins the cortex. When symptoms first appear, a small or large portion of the rhizome may be infected. Eventually, almost the entire differentiated vascular system is invaded. The infection may or may not pass into young budding suckers or mature 'daughter' suckers. Where it does, discoloration of vascular strands may be visible in the excised sucker. Usually, suckers less than 1.5 m tall and ca. 4 months old do not show external symptoms. Where wilt is epidemic and spreading rapidly, suckers are usually infected and seldom grow to produce fruit. Above- and below-ground parts of affected plants eventually rot and die.;Fusarium wilt was reported to occur on banana cultivars of the 'Mutika-Lujugira' (AAA genome) subgroup in East Africa above 1400 m. Internal symptoms were much less extensive than those described above and external symptoms more subtle, comprising thin pseudostems and small fingers. Nevertheless, symptomatic plants were recognized by smallholders and were rogued. These mild symptoms were initially believed to be indicative of an attack on a plant whose defences have been weakened as a result of cooler conditions or other predisposing factors at altitude (Ploetz et al., 1994). Given the importance of this banana group, also referred to locally as ÔEast African highland bananasÕ, to local trade and as a staple food, further investigation was merited. This revealed that the disorder also affected non-indigenous banana types, including Cavendish and Bluggoe (which were not affected by Fusarium wilt) and was related to abnormal soil nutrient levels and farm management practice. Discoloration similar to that caused by F. oxysporum f.sp. cubense was observed in vascular tissues of affected plants. Fusarium pallidoroseum (syn. Fusarium semitectum) was consistently isolated from such tissues but found to be non-pathogenic. F. oxysporum was not recovered (Kangire and Rutherford, 2001, Rutherford, 2006).

Hosts

F. oxysporum f.sp. cubense is one of around 100 formae speciales (special forms) of F. oxysporum which cause vascular wilts of flowering plants (Gerlach and Nirenberg, 1982). Hosts of the various formae speciales are usually restricted to a limited and related set of taxa. As currently defined, F. oxysporum f.sp. cubense affects the following species in the order Zingiberales: in the family Musaceae, Musa acuminata, M. balbisiana, M. schizocarpa and M. textilis, and in the family Heliconeaceae, Heliconia caribaea, H. chartacea, H. crassa, H. collinsiana, H. latispatha, H. mariae, H. rostrata and H. vellerigera (Stover, 1962, Waite, 1963). Additional hosts include hybrids between M. acuminata and M. balbisiana, and M. acuminata and M. schizocarpa.;F. oxysporum f.sp. cubense may survive as a parasite of non-host weed species. Three species of grass (Paspalum fasciculatum, Panicum purpurascens [ Brachiaria mutica ] and Ixophorus unisetus) and Commelina diffusa have been implicated (Waite and Dunlap, 1953).


Source: cabi.org
Solanum lycopersicum Leptochloa fusca Short
Description


Perennial, loosely tufted to rhizomatous. Culms erect or geniculate and rooting from lower nodes, up to 100 cm or more tall. Leaf sheaths glabrous;leaf blades tough, usually involute, 5-30(-50) × 0.15-0.3(-0.6) cm, adaxial surface scabrid, abaxial surface subglabrous;ligule 3-12 mm, acute. Inflorescence 15-25 cm, scabrid;racemes 3-28, indistinctly unilateral, 4-20 cm, straight, ascending or spreading, spikelets usually distant. Spikelets glaucous-green, subterete, 6-14 mm, florets 5-12;glumes keeled;lower glume lanceolate, 2-3 mm, acute;upper glume narrowly oblong, 3-4 mm, acute or mucronate;lemmas narrowly oblong, dorsally sub-rounded, lowest 4-5 mm, lower lateral veins pilose, entire or 2-dentate, midvein often produced into a short 0.3-1.6 mm awn;palea ciliolate along upper keels. Callus laterally pilose. Anthers 0.5-0.75(-2.5) mm. Caryopsis elliptic-oblong, 1.5-2.5 mm, dorso-ventrally flattened. Flowers from June to September (based on description of L. fusca ssp. fusca from Flora of China, 2014).

Impact

L. fusca is a perennial weed with a global distribution. It is an aggressive species showing a competitive advantage in many situations due to its tolerance of saline and alkaline soils and its likely ability to fix nitrogen. It is commonly a serious weed of rice in many countries, and is of particular concern in Spanish rice fields. It is recorded as invasive on Hawaii and in the Chagos Archipeligo (as L. fusca ssp. uninervia) (PIER, 2014) and has been the subject of an ‘eradication action’ in Europe (Brunel et al., 2013).

Hosts

L. fusca (mainly ssp. fasciculari) is a major weed of rice in a number of countries including USA, Cuba and Spain. L. fusca ssp. fusca is also problematic in rice in India and other countries. It can also occur in lucerne/alfalfa, tomatoes and turf.


Source: cabi.org
Solanum lycopersicum Xanthium spinosum
Description

D. sissoo is a medium to large, deciduous, long-lived tree with a spreading crown and thick branches. It attains a height of up to 30 m and a girth of 2.4 m;the bole is often crooked. In Rawalpindi district, Pakistan, it also occurs in the form of a straggling bush at an altitude of 1500 m, clinging to crevices in the sides of sandstone cliffs (Troup, 1921). The bark is thick, rough and grey, and has shallow, broad, longitudinal fissures exfoliating in irregular woody strips and scales (Luna, 1996). D. sissoo develops a long taproot from an early age and has numerous lateral ramifying roots (Hocking, 1993). The leaves are compound, imparipinnate and alternate, with rachis 3.5-8 cm long, swollen at the base. There are 3-5 leaflets, each 3.5-9 x 3-7 cm;leaflets alternate, broadly ovate, conspicuously and abruptly cuspidate at the apex, rounded at the base, entire, coriaceous, pubescent when young and glabrous when mature. The terminal leaflet is larger than the others, and there are 8-12 pairs of veins in the leaflets (Parker, 1956;Luna, 1996). The inflorescence of D. sissoo is an axillary panicle 3.5-7.5 cm long, with small flowers, 7-9 mm long, white to yellowish-white with a pervasive fragrance, sessile, papilionaceous and hermaphrodite. The standard petal is narrow at the base and forms a low claw;wing and keel petals are oblong. Pods are 4.5-10 x 0.7-1.5 cm, linear-oblong, indehiscent, stipitate, glabrous, apex acute, reticulate against the seeds, and usually 1-4 seeded. Seeds are kidney-shaped, variable in size (8-10 x 4-5.5 mm), pale brown, brown to brownish-black, reniform, compressed, with papery testa (Parker, 1956;Singh, 1989;Luna, 1996).


Source: cabi.org